I asked about the Electro-Harmonix 2A3 tubes at the 'other place' and heard all about Sovteks, Valve Art, TJ mesh plates......My amps have really old Sovteks in them and it's time to re-tube. Does anyone have experience with the new Electro-Harmonix 2A3's & 6SN7's? How do they sound compared to the Sovteks?